Until recently I believed
that there was such a thing as an optimal periodic table and that it was the
business of philosophers of chemistry to try to discover what this form might
be.More recently a couple of
developments have caused me to change my mind in a rather radical way.

Before discussing this change of mind let me backtrack a
little.In my 2007 book on the periodic
table, I not only claimed that there was one best possible form but also
suggested that it consisted of the left-step or Janet form of the periodic
table which places helium among the alkaline earth elements (Scerri, 2007).

In my more recent “A Very Short Introduction to the Periodic
Table”, I modified my view, although still maintaining that an optimal form was
a viable proposition.In this book I
wrote that it was not yet possible to decide between two candidates for the optimal
table (Scerri, 2011).In addition to the
very elegant left-step table I proposed a new form which places hydrogen at the
top of the halogen group in order to introduce a new atomic number triad
consisting of H(1), F(9) and Cl(17).Given that perfect atomic number triads crop up in about half of all
possible vertical groups of three elements in the periodic table it seems
reasonable to assume that the placement of a troublesome element like hydrogen
can be settled by moving it in order to create a new triad rather than keeping
it at the top of the alkali metals where it does not form a triad.

Returning to my first book, one of the things I did there
was to highlight some of ‘little people’
in the history of science, by which I mean intermediate and lesser known
personalities whose work was nevertheless very important in advancing our
knowledge of chemistry and physics. I am
referring to the likes of Anton Van den Broek, a Dutch economist who first
conceived of the idea of an atomic number for each element, which became the
basis for Henry Moseley’s famous experiments on this subject.

Another case is the British physicist Edmund Stoner, who was
the first to apply the newly discovered third quantum number to the assignment
of electronic configurations of atoms. This was soon adopted and taken further
by the enormously more famous Wolfgang Pauli, who introduced yet a fourth
quantum number that eventually became associated with electron spin.

My third, and most recent book published by OUP, is called
“A Tale of Seven Elements”, in which I delve into the way that the last seven
elements were discovered among the original 1-92 of the old periodic table
(Scerri, 2013).But why precisely seven?

This is because after Moseley had consolidated the concept
of atomic number it became clear that just seven elements remained to be
discovered.But this fact does not seem
to have lessened the number of priority disputes as well as claims and counter
claims that were made during these years which roughly speaking span the two
World Wars.

I also tried to think about the causes of priority disputes
among scientists and whether there is any underlying significance to this
phenomenon.I suggested that, whatever
the causes might be, the important thing is that science as a whole makes
progress while the fact that individual scientists involved in priority
disputes might have their egos bruised is of secondary importance.I began to think about science as one unified
whole, perhaps as a kind of living organism analogous to James Lovelock’s Gaia
which evolves while adapting to its environment.In the case of science as a whole the
environment would be the data that needs explaining and even the elements that
have yet to be discovered.This process
I suggest is a gradual one, rather than one which experiences sudden
revolutions in the way that Thomas Kuhn famously proposed (Kuhn, 1962).

The intermediate figures and lesser known little people
matter just as much as their better known counterparts like Bohr, Einstein and
Schrodinger.Science is a seamless
evolving process and this is better appreciated by including the important
intermediate steps that the little people provided.

Appreciating the nature of science requires a view from afar
which focuses on the overall evolution of ideas, experiments and even entities
like elements rather than on individual famous scientists or their theories.Moreover, theories should not be considered
as being ‘right’ or ‘wrong’ just as the various steps that occur in the
biological evolution of a species are not right or wrong but simply vary in
terms of their adaptation to their environment.

According to this view science does not develop towards some
truth that lies beckoning ahead of us, but it just develops in order to better
cope with the environment or situation that science finds itself in at any
particular epoch.All of this amounts to
a rather pluralistic view of science in which we consider and value the work of
the little people who may only have made transitional contributions, or even
some that may appear to have been wrong-headed ideas.

At the same time as these ideas were starting to occur to me
I traveled to Uruguay and Argentina to give some lectures at a couple of international
conferences.I met up with an old friend
and colleague, Hasok Chang, who is now at the University of Cambridge and who
gave an interesting lecture in which he argued in favor of pluralism in
science.Chang stressed the need to hold
alternative approaches to one and the same scientific problem at any given
time.He criticized the monist view that
it is important to weed out all but one viable approach or theory in any given
situation.He too does not believe that
there is one objective truth.Chang
believes that the concept of phlogiston should not have been abandoned as
rapidly as it was at the time of Lavoisier’s chemical revolution (Chang, 2012).Coming to the contemporary situation, he does
not believe that Steven Weinberg’s “dream of a final theory” is ever going to materialize.

Rather than dwelling
too much on Chang’s views let me get back to the periodic table with which this
blog began.What do all these ideas
imply about the notion of an optimal periodic table that I have been so keen to
support in the past?I now think that I
was wrong to expect there to be one best table, as though there is one Platonic
form that science is striving towards.

Rather than just
pointing out the pros and cons of a couple of candidate forms of the periodic
table, as I did in my VSI, I now want to go on record as renouncing altogether
the idea of an optimal periodic table.My growing view of the gradual evolution of science and the fact that it
involves the whole scientific community, whether competing individual
scientists realize this or not, is telling me that science does not progress
towards an external ‘truth’.

I no longer see science as being teleological and again this
reflects its essentially biological nature, since evolutionary biology we have
long realized does not have a telos or
end point.Developments in science,
including the development of the periodic table grows from within while looking
at past science and not at some magical external goal.And here I believe that Kuhn had it right, in
his influential book, by insisting that scientific development is ‘pushed from
behind’ rather than having a teleological nature (Kuhn, 1962).

This will not stop me from debating the relative virtues of
various forms of the periodic table, nor will it blunt my critical faculties
when confronted with what I consider to be an inconsistent system.But I will finally drop the monistic
insistence on there being one best periodic table.

About Me

Lecturer at UCLA in Los Angeles teaching chemistry and philosophy of science.
Author of The Periodic Table, Its Story and Its Significance, Oxford University Press, 2007, A Very Short Introduction to the Periodic Table, Oxford University Press, 2011, A Tale of Seven Elements, Oxford University Press, 2013. See website for other books.